Synthesis and Photophysical Properties of Star-Shaped Triphenylamine Trimers Functionalized With BODIPY and Subphthalocyanine Chromophores.

This work reports the synthesis, characterization, and solution photophysical properties of para-trisubstituted triphenylamine (TPA) derivatives that preserve the threefold symmetry around the central nitrogen atom. By functionalizing the TPA core with three units of one of two representative boron-containing chromophores-BODIPY and subphthalocyanine (SubPc)-we directly compare how chromophore identity and molecular topology determine the optical response of the resulting star-shaped architectures. Whereas neither family exhibits significant solvatochromism in absorption, their fluorescence is strongly governed by both the solvent and the molecular architecture. The SubPc-based trimer undergoes efficient fluorescence quenching in all but the least polar solvent studied (Φ ≤ 2%, partially restored to 10% in methylcyclohexane), consistent with an effective intramolecular excited-state deactivation pathway. In contrast, the BODIPY-based trimer remains strongly quenched in polar media while developing a new red-shifted emission band (λem = 606 nm) with a markedly enhanced fluorescence quantum yield (Φ = 26%) in toluene. Comparison with the corresponding monomeric reference compounds demonstrates that these distinctive photophysical properties arise primarily from the threefold star-shaped architecture rather than from the intrinsic optical properties of the individual chromophores. These findings establish molecular topology as an effective design parameter for tuning excited-state dynamics in multichromophoric TPA-based systems.